The present invention relates to a method and a system for determining state variables of an electric motor for driving a motor vehicle.
The knowledge of the rotor angle of the electric motor can be necessary for controlling rotary field motors or electric motors in order to be able to exactly set a required torque. In order to ascertain the rotor position, i.e. the rotor angle, a sensor is typically mounted on the rotor of the electric motor, which detects the rotor position. Alternatively, the rotor angle can be acquired by means of sensorless methods. Sensorless methods are methods which run without the use of a pattern converter, which is also referred to as a pattern generator or simply generator.
In the European patent EP 2555417 A1 a method for determining an absolute rotor angle with the aid of a wheel sensor is described, wherein an initial angle of the rotor of an electric motor is determined by means of a pole position identification.